A separate control system may be configured for a combined sensor device. Alternatively, at least part of the control system may be included in another device, such as a processor of a mobile device. Software for handwriting, touch and fingerprint detection may be included in the control system. Low, medium and high resolution may be obtained with a single combined sensor device by scanning a subset of the sensels, or by aggregating lines or columns. Power consumption may be reduced by aggregating sensor pixels (or rows or columns) electrically using the controller, so that they perform as a low power small array until higher resolution with a larger array is needed. Power consumption may be reduced by turning off portions or all of the sensor device, turning off parts of the control system, and/or employing first-level screening at a reduced frame rate.